1. Field of the Invention
The present invention relates to a wiper device for wiping a windshield glass of an automobile and a method of manufacturing a hollow frame for a wiper device.
2. Description of the Related Art
A wiper device, which wipes a windshield glass of an automobile, wipes off rain drops and the like on the windshield glass in such a manner that a wiper arm mounted to a pivot shaft reciprocates pivotally in a predetermined range by the rotation of the pivot shaft.
In such a wiper device, the pivot shaft is rotatably supported by a wiper bracket having a pivot holding portion. The wiper bracket is fixed to a vehicle body (e.g., a cowl panel or a suspension tower disposed below the windshield glass) by means of mounting bolts. In a vehicle having a pair of wiper arms and blades, pivot shafts are respectively provided at both sides of the vehicle in the transverse direction thereof, and wiper brackets for supporting these pivot shafts are also respectively fixed to both sides of the vehicle body in the transverse direction. Further, there are what are known as frame-integrated type wiper devices, in which a pair of wiper brackets are formed integrally with a frame serving as a support base for a wiper motor or the like (e.g., Japanese Patent Application Laid-Open (JP-A) No. 9-175336, Japanese Utility Model Laid-Open (JP-U) No. 7-31525, or Japanese Utility Model Laid-Open (JP-U) No. 5-22226).
In a wiper device disclosed in the above-mentioned Japanese Patent Application Laid-Open (JP-A) No. 9-175336, an overall assembly of a motor and a link is formed by welding and fixing a bracket to a support pipe (a pipe frame) which connects a pair of pivot holders to each other, and mounting and fixing a wiper motor to the bracket. This can provide a relatively simple and compact structure.
However, in a structure such as the above wiper device in which the support pipe (the pipe frame) is formed integrally with the pivot holders, the positions at which respective pivot holders located at both end portions of the support pipe are mounted to a vehicle body, and the position at which the wiper motor is mounted are determined by necessity (as a matter of course). Namely, no degree of freedom is provided for the mounting of this frame assembly (respective pivot holders) to the vehicle body. Further, depending on the size of the vehicle (the transverse dimension of the vehicle, mounting positions or the like), the positions of the pivot holders to be fixed to the end portions of the support pipe may be incompatible, or the position at which the wiper motor is mounted may have to be changed. Therefore, there is a drawback in that many types of support pipes (i.e., wiper devices) have to be prepared for each vehicle having a different size or layout.
In a wiper device disclosed in Japanese Utility Model Laid-Open (JP-U) No. 7-31525 mentioned above, an overall assembly of a motor and a link is formed by welding and fixing a bracket to a support pipe (a pipe frame) which connects a pair of pivot holders to each other, and mounting and fixing a wiper motor to the bracket. This can provide a relatively simple and compact structure. Moreover, this device has an advantage in that adjustment of the angle of the motor mounting surface of the bracket is made possible upon mounting of the frame assembly (respective pivot holders) to the vehicle body by relatively rotating the pivot holders and the support pipe around the axes thereof and adjusting the state of the connection between the pivot holders and the support pipe.
However, in the case of the support pipe which is made hollow in the longitudinal direction thereof, there is a drawback in that the support pipe deforms undesirably when measures, such as fastening, riveting or the like, are taken for applying fastening force or pressure to the support pipe so as to directly fix the wiper motor to the support pipe (the pipe frame).
As a frame which is not deformed by pressure at the time of fixing the wiper motor thereto, there exists a bar-shaped frame of a wiper device disclosed in Japanese Utility Model Laid-Open (JP-U) No. 5-22226. The frame is formed by bending a steel plate and has a substantially U-shaped cross-section extending over the entire length thereof in the longitudinal direction. However, a drawback arises in that the frame has lower flexural strength than a pipe frame. Moreover, since the bar-shaped frame is formed so as to have a substantially U-shaped cross-section extending over the entire length thereof in the longitudinal direction, when a wiper device is manufactured in such a manner that a wiper motor is directly fixed to the bar-shaped frame by bolts or rivets, an angle of a surface (i.e., an angle of a planar portion) of the bar-shaped frame to which the wiper motor is mounted is determined by necessity (as a matter of course) due to its cross-sectional configuration (the substantially U-shaped configuration). In other words, there is a drawback in that an output shaft of the wiper motor cannot be disposed at an arbitrary angle or position around the axis of the frame.
All of the conventional frame-integrated type wiper devices described above have both advantages and drawbacks, and a wiper device which can overcome the above drawbacks has been desired.
In view of the aforementioned circumstances, a first object of the present invention is to provide a wiper device and a method of manufacturing a hollow frame for a wiper device, in which firm fixing is obtained without any special fixing parts being required to a frame which is relatively lightweight and has a high rigidity and strength, and the frame is not subjected to deformation even when a separate member is firmly fixed to the frame.
In view of the aforementioned facts, a second object of the present invention is to provide a wiper device in which frames having many different sizes can be formed by changing combinations of the frames, and which can be applied to vehicles having different sizes and layouts and can freely set the direction in which a drive source is fastened and fixed to the frame around the axis thereof.
In view of the aforementioned circumstances, a third object of the present invention is to provide a method of manufacturing a hollow frame for the wiper device described above.
In order to achieve the first object of the present invention, in accordance with a first aspect of the present invention, there is provided a wiper device comprising: a plurality of pivot shafts, each pivot shaft having a distal end portion to which a wiper arm is fixed; a plurality of pivot holders fixed to a vehicle body, each pivot holder rotatably supporting each of the plurality of pivot shafts; a hollow frame connecting each of the plurality of pivot holders to each other; a drive source fixed to the hollow frame; and a link rod for transmitting a driving force generated by the drive source to each of the plurality of pivot shafts, wherein the hollow frame includes a mounting portion formed so as to be non-hollow by flattening the intermediate portion of the hollow frame in the longitudinal direction thereof, and the drive source is fixed to the mounting portion.
In this wiper device, the pivot holders, each of which rotatably supports the pivot shaft, are connected to each other via the hollow frame, and the drive source is fixed directly to the mounting portion (the flat bearing surface for mounting) of the hollow frame, thereby forming the assembly as a whole. This assembly is fixed to a vehicle body structural member provided below the windshield glass.
Here, since the wiper device employs a hollow frame, the frame as a whole has a high rigidity and is lightweight in essence. Further, the mounting portion having the flat bearing surface for mounting is formed at the intermediate position of the hollow frame in the longitudinal direction, and the drive source is fixed directly to the mounting portion (the flat bearing surface for mounting) of the hollow frame. Therefore, even when the drive source is firmly fixed to the mounting portion, the hollow frame is not subjected to deformation.
In addition, since the drive source is fixed directly to the mounting portion (i.e., the flat bearing surface for mounting) of the hollow frame as described above, the mounting angle of the drive source relative to the hollow frame is set with stability.
As described above, the wiper device according to the first aspect is lightweight and has a high rigidity and strength. Further, in this wiper device, firm fixing to the frame is obtained without other special fixing parts being required, and the frame is not subjected to deformation even when the drive source is firmly fixed to the frame.
In order to achieve the second object of the present invention, in accordance with a second aspect of the present invention, there is provided a wiper device comprising: a plurality of pivot shafts, each pivot shaft having a distal end portion to which a wiper arm is fixed; a plurality of pivot holders fixed to a vehicle body, each pivot holder rotatably supporting each of the plurality of pivot shafts; a hollow frame connecting each of the plurality of pivot holders to each other; a drive source fixed to the hollow frame; and a link rod for transmitting a driving force generated by the drive source to each of the plurality of pivot shafts, wherein the hollow frame is formed by a pair of split frames, each split frame including a mounting portion having a flat bearing surface for mounting to which surface the drive source is directly fixed, the mounting portion being formed so as to be non-hollow with a substantially U-shaped cross-section by flattening one end portion of a hollow base material, and a connecting portion, which is the other end portion of the hollow base material formed so as to have an annular cross-section and connected to the pivot holder, and the mounting portion of one of the pair of split frames and the mounting portion of the other of the pair of split frames are overlapped with each other so as to be connected and fixed to each other.
In this wiper device, the pivot holders, each of which rotatably supports the pivot shaft, are connected to each other via the hollow frame, and the drive source is fixed directly to the mounting portion (the flat bearing surface for mounting) of the hollow frame, thereby forming an assembly as a whole. This assembly is fixed to a vehicle body structural member provided below the windshield glass.
Here, the hollow frames in the wiper device are formed from the pair of split frames. Each split frame includes the mounting portion having the flat bearing surface for mounting to which surface the drive source is directly fixed, and the hollow (having an annular cross-section) connecting portion which is connected to the pivot holder. The mounting portions of the pair of split frames overlap with each other so that the pair of split frames are connected and fixed to each other.
Therefore, by preparing various types of split frames having different lengths or the like (e.g., those having connecting portions or the like with different lengths) and changing the combinations of the split frames so as to form a pair of split frames, many types of hollow frames can be formed using a few types of split frames. Namely, an optimum hollow frame for the size of the vehicle (the transverse dimension of the vehicle, and the positions at which the pivot holders are mounted) can be formed by changing the combinations of the split frames.
In addition, the connecting portion of the hollow frame by which the hollow frame is connected to the pivot holder is formed so as to have an annular cross-section, and is fitted together with and connected to the pivot holder. Therefore, adjustment and setting of the mounting angle of the mounting portion of the hollow frame relative to the vehicle body, i.e., the mounting angle of the drive source relative to the vehicle body is made possible by pivoting the hollow frame around the axis thereof in accordance with the state in which the pivot holders are mounted, which state is determined in accordance with the type of the vehicle body. Namely, the direction in which the drive source is fastened and fixed to the hollow frame is not limited, and degree of freedom is provided for the direction.
As described above, in the wiper device according to the second aspect of the present invention, hollow frames having many different sizes can be formed by changing the combinations of the split frames and can be applied to vehicles having different sizes and layouts. Further, it is possible to freely set the direction in which the drive source is fastened and fixed to the frame around the axis thereof.
In order to achieve the third object of the present invention, in accordance with a third aspect of the present invention, there is provided a method of manufacturing a hollow frame for a wiper device comprising a plurality of pivot holders fixed to a vehicle body, each pivot holder rotatably supporting a pivot shaft to whose distal end portion a wiper arm is fixed, a hollow frame connecting each of the plurality of pivot holders to each other, a drive source fixed to the hollow frame, and a link rod for transmitting a driving force generated by the drive source to the pivot shaft, wherein a mounting portion having a non-hollow, U-shaped cross-section is formed at the intermediate portion of the hollow frame in the longitudinal direction by press-working the cross-sectionally annular shaped, hollow base material, the mounting portion having a flat bearing surface for mounting to which surface the drive source is directly fixed.
In the method of manufacturing a hollow frame for a wiper device according to the third aspect, a mounting portion having the flat bearing surface for mounting and whose cross-section is substantially U-shaped is formed in the hollow frame so as to be non-hollow by press-working a portion of the hollow base material having an annular cross-section . Since the drive source is fixed directly to this mounting portion, the mounting angle of the drive source relative to the hollow frame is set with stability.
As described above, in the method of manufacturing a hollow frame for a wiper device according to the third aspect of the present invention, it is possible to easily manufacture a hollow frame, which is lightweight and has a high rigidity and strength, and relative to which the mounting angle of the drive source can be set with stability.